The invention discloses a method for fixing a magnetic core in a PCB (Printed Circuit Board) taphole. The method comprises the following steps of: (1) material preparation: preparing a core plate; (2) drilling: drilling a through hole and a depth control hole on the core plate, wherein the through hole and the depth control hole form a step hole, and the diameter of the through hole is smaller than that of the depth control hole; (3) magnetic core placement: placing a magnetic core on the step of the step hole of the core plate and filling resin in the magnetic core, wherein the magnetic core is arranged in the depth control hole; and (4) press-fitting: sequentially press-fitting a prepreg and a copper foil on the surface of the core plate. In the method, the magnetic core is directly placed in the step hole of the core plate, i.e. the magnetic core is fixed by utilizing the step of the step hole, the magnetic core is firmly fixed, and resin is conveniently to fill in the magnetic core. In addition, the prepreg and the copper foil are sequentially press-fitted on the surface of the core plate, i.e. the copper foil and the core plate with the magnetic core are bonded together through the prepreg, thus the magnetic core can be more firmly fixed. The magnetic core is fixed by adopting a press-fitting mode, thus the processing method is simple, convenient to operate and convenient for subsequent processing.